<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <title>canvas爱心</title>
         
         <style>
             html, body {
               height: 100%;
                 padding: 0;
                   margin: 0;
                     background: #000;
                     }
                     canvas {
                       position: absolute;
                         width: 100%;
                           height: 100%;
                           }</style>
                           </head>
                           <body>
                                
                                <canvas id="pinkboard"></canvas>
                                 
                                 <script>
                                     /*
                                      * Settings
                                       */
                                       var settings = {
                                         particles: {
                                             length:   500, // maximum amount of particles
                                                 duration:   2, // particle duration in sec
                                                     velocity: 100, // particle velocity in pixels/sec
                                                         effect: -0.75, // play with this for a nice effect
                                                             size:      30, // particle size in pixels
                                                               },
                                                               };
                                                                
                                                                /*
                                                                 * RequestAnimationFrame polyfill by Erik M?ller
                                                                  */
                                                                  (function(){var b=0;var c=["ms","moz","webkit","o"];for(var a=0;a<c.length&&!window.requestAnimationFrame;++a){window.requestAnimationFrame=window[c[a]+"RequestAnimationFrame"];window.cancelAnimationFrame=window[c[a]+"CancelAnimationFrame"]||window[c[a]+"CancelRequestAnimationFrame"]}if(!window.requestAnimationFrame){window.requestAnimationFrame=function(h,e){var d=new Date().getTime();var f=Math.max(0,16-(d-b));var g=window.setTimeout(function(){h(d+f)},f);b=d+f;return g}}if(!window.cancelAnimationFrame){window.cancelAnimationFrame=function(d){clearTimeout(d)}}}());
                                                                   
                                                                   /*
                                                                    * Point class
                                                                     */
                                                                     var Point = (function() {
                                                                       function Point(x, y) {
                                                                           this.x = (typeof x !== 'undefined') ? x : 0;
                                                                               this.y = (typeof y !== 'undefined') ? y : 0;
                                                                                 }
                                                                                   Point.prototype.clone = function() {
                                                                                       return new Point(this.x, this.y);
                                                                                         };
                                                                                           Point.prototype.length = function(length) {
                                                                                               if (typeof length == 'undefined')
                                                                                                     return Math.sqrt(this.x * this.x + this.y * this.y);
                                                                                                         this.normalize();
                                                                                                             this.x *= length;
                                                                                                                 this.y *= length;
                                                                                                                     return this;
                                                                                                                       };
                                                                                                                         Point.prototype.normalize = function() {
                                                                                                                             var length = this.length();
                                                                                                                                 this.x /= length;
                                                                                                                                     this.y /= length;
                                                                                                                                         return this;
                                                                                                                                           };
                                                                                                                                             return Point;
                                                                                                                                             })();
                                                                                                                                              
                                                                                                                                              /*
                                                                                                                                               * Particle class
                                                                                                                                                */
                                                                                                                                                 
                                                                                                                                                 var Particle = (function() {
                                                                                                                                                   function Particle() {
                                                                                                                                                       this.position = new Point();
                                                                                                                                                           this.velocity = new Point();
                                                                                                                                                               this.acceleration = new Point();
                                                                                                                                                                   this.age = 0;
                                                                                                                                                                     }
                                                                                                                                                                       Particle.prototype.initialize = function(x, y, dx, dy) {
                                                                                                                                                                           this.position.x = x;
                                                                                                                                                                               this.position.y = y;
                                                                                                                                                                                   this.velocity.x = dx;
                                                                                                                                                                                       this.velocity.y = dy;
                                                                                                                                                                                           this.acceleration.x = dx * settings.particles.effect;
                                                                                                                                                                                               this.acceleration.y = dy * settings.particles.effect;
                                                                                                                                                                                                   this.age = 0;
                                                                                                                                                                                                     };
                                                                                                                                                                                                       Particle.prototype.update = function(deltaTime) {
                                                                                                                                                                                                           this.position.x += this.velocity.x * deltaTime;
                                                                                                                                                                                                               this.position.y += this.velocity.y * deltaTime;
                                                                                                                                                                                                                   this.velocity.x += this.acceleration.x * deltaTime;
                                                                                                                                                                                                                       this.velocity.y += this.acceleration.y * deltaTime;
                                                                                                                                                                                                                           this.age += deltaTime;
                                                                                                                                                                                                                             };
                                                                                                                                                                                                                               Particle.prototype.draw = function(context, image) {
                                                                                                                                                                                                                                   function ease(t) {
                                                                                                                                                                                                                                         return (--t) * t * t + 1;
                                                                                                                                                                                                                                             }
                                                                                                                                                                                                                                                 var size = image.width * ease(this.age / settings.particles.duration);
                                                                                                                                                                                                                                                     context.globalAlpha = 1 - this.age / settings.particles.duration;
                                                                                                                                                                                                                                                         context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);
                                                                                                                                                                                                                                                           };
                                                                                                                                                                                                                                                             return Particle;
                                                                                                                                                                                                                                                             })();
                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                              /*
                                                                                                                                                                                                                                                               * ParticlePool class
                                                                                                                                                                                                                                                                */
                                                                                                                                                                                                                                                                var ParticlePool = (function() {
                                                                                                                                                                                                                                                                  var particles,
                                                                                                                                                                                                                                                                        firstActive = 0,
                                                                                                                                                                                                                                                                              firstFree   = 0,
                                                                                                                                                                                                                                                                                    duration    = settings.particles.duration;
                                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                        function ParticlePool(length) {
                                                                                                                                                                                                                                                                                            // create and populate particle pool
                                                                                                                                                                                                                                                                                                particles = new Array(length);
                                                                                                                                                                                                                                                                                                    for (var i = 0; i < particles.length; i++)
                                                                                                                                                                                                                                                                                                          particles[i] = new Particle();
                                                                                                                                                                                                                                                                                                            }
                                                                                                                                                                                                                                                                                                              ParticlePool.prototype.add = function(x, y, dx, dy) {
                                                                                                                                                                                                                                                                                                                  particles[firstFree].initialize(x, y, dx, dy);
                                                                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                                                          // handle circular queue
                                                                                                                                                                                                                                                                                                                              firstFree++;
                                                                                                                                                                                                                                                                                                                                  if (firstFree   == particles.length) firstFree   = 0;
                                                                                                                                                                                                                                                                                                                                      if (firstActive == firstFree       ) firstActive++;
                                                                                                                                                                                                                                                                                                                                          if (firstActive == particles.length) firstActive = 0;
                                                                                                                                                                                                                                                                                                                                            };
                                                                                                                                                                                                                                                                                                                                              ParticlePool.prototype.update = function(deltaTime) {
                                                                                                                                                                                                                                                                                                                                                  var i;
                                                                                                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                                                                                          // update active particles
                                                                                                                                                                                                                                                                                                                                                              if (firstActive < firstFree) {
                                                                                                                                                                                                                                                                                                                                                                    for (i = firstActive; i < firstFree; i++)
                                                                                                                                                                                                                                                                                                                                                                            particles[i].update(deltaTime);
                                                                                                                                                                                                                                                                                                                                                                                }
                                                                                                                                                                                                                                                                                                                                                                                    if (firstFree < firstActive) {
                                                                                                                                                                                                                                                                                                                                                                                          for (i = firstActive; i < particles.length; i++)
                                                                                                                                                                                                                                                                                                                                                                                                  particles[i].update(deltaTime);
                                                                                                                                                                                                                                                                                                                                                                                                        for (i = 0; i < firstFree; i++)
                                                                                                                                                                                                                                                                                                                                                                                                                particles[i].update(deltaTime);
                                                                                                                                                                                                                                                                                                                                                                                                                    }
                                                                                                                                                                                                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                                                                                                                                                                                            // remove inactive particles
                                                                                                                                                                                                                                                                                                                                                                                                                                while (particles[firstActive].age >= duration && firstActive != firstFree) {
                                                                                                                                                                                                                                                                                                                                                                                                                                      firstActive++;
                                                                                                                                                                                                                                                                                                                                                                                                                                            if (firstActive == particles.length) firstActive = 0;
                                                                                                                                                                                                                                                                                                                                                                                                                                                }
                                                                                                                                                                                                                                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                                                                                                                                                                                                                          };
                                                                                                                                                                                                                                                                                                                                                                                                                                                            ParticlePool.prototype.draw = function(context, image) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                // draw active particles
                                                                                                                                                                                                                                                                                                                                                                                                                                                                    if (firstActive < firstFree) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                          for (i = firstActive; i < firstFree; i++)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  particles[i].draw(context, image);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          if (firstFree < firstActive) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                for (i = firstActive; i < particles.length; i++)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        particles[i].draw(context, image);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              for (i = 0; i < firstFree; i++)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      particles[i].draw(context, image);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            };
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              return ParticlePool;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              })();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               /*
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                * Putting it all together
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 */
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 (function(canvas) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   var context = canvas.getContext('2d'),
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         particles = new ParticlePool(settings.particles.length),
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               particleRate = settings.particles.length / settings.particles.duration, // particles/sec
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     time;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         // get point on heart with -PI <= t <= PI
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           function pointOnHeart(t) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               return new Point(
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     160 * Math.pow(Math.sin(t), 3),
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               );
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     // creating the particle image using a dummy canvas
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       var image = (function() {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           var canvas  = document.createElement('canvas'),
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   context = canvas.getContext('2d');
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       canvas.width  = settings.particles.size;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           canvas.height = settings.particles.size;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               // helper function to create the path
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   function to(t) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         var point = pointOnHeart(t);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           return point;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   // create the path
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       context.beginPath();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           var t = -Math.PI;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               var point = to(t);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   context.moveTo(point.x, point.y);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       while (t < Math.PI) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             t += 0.01; // baby steps!
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   point = to(t);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         context.lineTo(point.x, point.y);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 context.closePath();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     // create the fill
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         context.fillStyle = '#ea80b0';
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             context.fill();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 // create the image
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     var image = new Image();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         image.src = canvas.toDataURL();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             return image;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               })();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   // render that thing!
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     function render() {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         // next animation frame
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             requestAnimationFrame(render);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     // update time
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         var newTime   = new Date().getTime() / 1000,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 deltaTime = newTime - (time || newTime);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     time = newTime;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             // clear canvas
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 context.clearRect(0, 0, canvas.width, canvas.height);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         // create new particles
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             var amount = particleRate * deltaTime;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 for (var i = 0; i < amount; i++) {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             var dir = pos.clone().length(settings.particles.velocity);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               // update and draw particles
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   particles.update(deltaTime);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       particles.draw(context, image);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             // handle (re-)sizing of the canvas
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               function onResize() {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   canvas.width  = canvas.clientWidth;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       canvas.height = canvas.clientHeight;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         }
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           window.onresize = onResize;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               // delay rendering bootstrap
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 setTimeout(function() {
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     onResize();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         render();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           }, 10);
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           })(document.getElementById('pinkboard'));</script>
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            </body>
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            </html>
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              